A solid support with a nucleic acid immobilized on its surface is known as a useful material for the techniques of detecting, isolating and purifying nucleic acids containing the desired specific base sequence. This technique is a method developed by scientists in the field of recombinant DNA technology, the application of which is based on the observation that DNA or RNA denatured to the single-stranded form can hybridize with other single-stranded nucleic acids containing substantially complementary base sequences through hydrogen bonding between the bases under suitable conditions.
As a method of immobilizing a single-stranded nucleic acid on the surface of solid support, a method was developed which comprised bringing a solid support composed of materials having high affinities for nucleic acids such as nitrocellulose or nylon membranes into contact with a nucleic acid, trapping the nucleic acid on the support and then baking or UV irradiating the resulting support to strengthen the immobilization. This method, however, is undesirable because nucleic acids that lack the desired specific base sequence in a sample and nucleic acid detection probes are also likely to be trapped on the surface of the support because of the high nonspecific affinity of the solid support for nucleic acids. To prevent such nonspecific binding, this method requires very tedius operations of coating the surface of the support with a polymeric substance foreign to the desired specific base sequence, and repeated washing of the support after a hybrid is formed.
To overcome the problems described above, various nucleic acid immobilization supports and their manufacturing processes have been proposed. Among these is a support that immobilizes a nucleic acid through a carbon chain having 4 to 20 carbon atoms (part of the carbon atoms may be substituted with a heteroatom such as O, N, S or the like and this chain is referred to as "arm") between a nucleotide sequence-part constituting the nucleic acid and a support. This nucleic acid immobilization support is manufactured by previously activating a given part of a base in a nucleotide to produce an immobilization site and then reacting the activated part with a reactive residue provided for the support as an "arm", to form a covalent bond (Japanese Patent Application Kokai No. 130305/1986). A method of ligating a nucleic acid to a support using an enzymatic reaction has also been described (Japanese Patent Application Kokai No. 246201/1986).
However, the method described in the official gazette of Japanese Patent Application Kokai No. 130305/1986 requires the protection of other reactive residues in a nucleic acid by protective residues, at the time a given part of a base is activated. In addition, it is necessary to completely eliminate the protective residues after immobilizing the nucleic acid on the support. During the elimination of the protective residues, several changes of reaction solvent and recovery and purification of the reaction product are required. Furthermore, the reaction can be a very lengthy operation, sometimes taking several hours to several days to carry out.
The method described in the official gazette of Japanese Patent Application Kokai No. 24601/1986 requires the ligation of a nucleic acid in a given direction to increase the effective amount of immobilized nucleotide or oligonucleotide. Thus remarkably tedious operations are also required for this method. In addition, large amounts of an expensive enzyme are required, making this method economically disadvantageous.
Consequently, the above methods are impractical for daily use.